1. Field of the Invention
This invention relates generally to an active template grid system. More particularly, it relates to an active template system for positioning medical implants. Still more particularly this invention relates to a template grid system for use with transrectal ultrasound imaging probes in brachytherapy and cryosurgery for cancerous prostate and related surgeries, where the template has sensors embedded in it to detect the presence of the seed-delivering, or freezing needles.
2. Background Art
As illustrated in FIG. 1 of U.S. Pat. No. 6,422,997, and in FIG. 1 of United States Patent Publication 20040152986 (the entire contents of which are incorporated by reference herein), brachytherapy is performed with the patient in the lithotomy position, using an ultrasound imaging probe placed in the rectum to monitor seed placement. A template grid arrangement or guide plate having openings at predefined positions of a coordinate grid thereon, of the general type illustrated in FIG. 3 of U.S. Pat. No. 6,387,034, which is kept in precise linear orientation with the ultrasound probe, must be accurately oriented adjacent the perineum in relation to the prostate, and locked in position throughout the procedure to achieve optimum seed placement. A cradle of the type illustrated in FIG. 17 of U.S. Pat. No. 6,752,753 is helpful in this regard. Precise and reproducible orientation and positioning of the ultrasound imaging probe in the rectum is a key element in both the calculations required for determining the number and distribution of radioactive seeds required for treatment and their subsequent placement using preloaded needles guided by the peritoneal template and real time ultrasound imaging.
Even with proper probe positioning, placement of the needles using the template grid needs to be accurate and precisely coordinated with the images from the probe and the patient's anatomy to have effective therapy. Keeping track of the actual needles inserted can also be problematic during the procedure.